1. Field of the Invention
This invention relates to a process for remanufacturing a charging member. This invention also relates to a charging member remanufactured by the remanufacturing process and a process cartridge having such a charging member.
2. Related Background Art
In electrophotographic image forming apparatus such as copying machines, laser beam printers and facsimile machines, various charging members, e.g., development charging rollers, transfer charging rollers and primary charging rollers have been used. Almost all of these charging rollers have been used up and have not been reused. Also, any rejected products caused during their manufacture can not be used as products and hence have been discarded without being repaired.
This is because these charging rollers have had the problem that, when repeatedly applied to electrophotographic processes, they cause a lowering of their electrical properties and no longer exhibit the electrical properties of the same level as the initial stage. The lowering of electrical properties of various charging members may be caused by, e.g., surface deterioration of charging members which is due to the effect of ozone or the like generated by discharge at the time of charging, and surface wear of charging members which is caused by their contact with materials or members to be charged by the charging members.
There is another problem that the surface wear of charging members, caused by their contact with materials or members to be charged by them, may damage surface properties such as lubricity and smoothness.
During repeated use of the charging rollers, powdery developer (toner) and paper dust also may adhere to the whole surfaces or peripheries of their outermost layers.
If such charging rollers are reused without means such as cleaning, the contamination of their surfaces makes surface resistance of charging rollers uneven especially in an environment of low humidity and low temperature to cause non-uniform charging. The charging rollers having caused a lowering of charging performance tend to be affected by such contamination of surfaces.
In addition, the charging members provided in the above electrophotographic apparatus are not limited to those having a single-layer structure, and those having a multi-layer structure, comprising a plurality of layers overlaid one another, are widely used. When the charging members are formed in the multi-layer structure, means such as coating is commonly used. When the layers are formed by coating, defective coatings such as uneven coatings, uneven coating thickness and spitting may occur in some cases. The presence of such defective coatings in charging members makes the surface resistance delicately uneven at that portion to enable no uniform charging to cause faulty images.
Meanwhile, recently, ecology (the advocacy of protection of the global environment from destruction and pollution for the purpose of gentle coexistence in the global environment) is spreading worldwide. From the viewpoint of the saving of global natural resources and the protection of environment, studies are also made on the charging members for the electrophotographic apparatus so that they can be remanufactured and reused in some way.
As methods of remanufacturing charging members, a method is known in which the surfaces of members are cleaned with a solvent to remove contamination.
Since, however, the surface layers of charging members are mostly those containing synthetic resin, synthetic rubber or the like, the above prior art cleaning method is not preferable for the following reasons (A) and (B).
(A) Synthetic resins and synthetic rubbers tend to dissolve upon contact with the cleaning solvent or cause cracks, and there is a possibility of damaging various properties required in charging members of this type, such as electrical resistance, hardness, surface roughness, roundness, straightness and lubricity (frictional coefficient).
(B) The charging members of this type are not limited to those having a single-layer structure, and those having a multi-layer structure are widely used. In the case of multi-layer rollers, the cleaning solvent may soak through the layers from the edges of rollers, and care must be taken not only for solvent resistance of surface layer materials but also solvent resistance of inside materials. This not only imposes limitations on the types of cleaning solvents used but also causes a possibility of a decrease in adhesion between layers.
An object of the present invention is to settle the problems discussed above, to provide a process for remanufacturing a charging member in order to obtain a charging member having the same good performances as virgin products.
Another object of the present invention is to provide a charging member remanufactured by such a remanufacturing process and a process cartridge having the charging member thus obtained.
The present invention provides a process for remanufacturing a charging member having at least two layers on a conductive support, the process comprising the steps of;
carrying out mechanical abrasion to remove at least a surface layer provided on the charging member; and
forming a layer on the surface laid bare by the abrasion.
The present invention also provides a charging member remanufactured by the above remanufacturing process, and a process cartridge having such a charging member.